Twist-off safety coupling



jam., 5? i932. C, MAUNOWSK; LS

TWISTOFF SAFETY COUPLING Filed June 17, 1929 2 Sheets-Sheet l mmm jam 59E932, c, MALnNom/sm TWIST-OFF' SAFETY COUPLING Filed June 17, 1929 2Sheets-Sheet 2 Patented Jan. 5, 1932 PATENT GFFICE CHESTER MALINOWSXI, FLOS ANGELES, CALIFORNIA TWIST-OFF SAFETY COUPLING Application filed June17,

This invention relates to a device for preventing loss of drill pipe inthe operation of well drilling due to breakingoff or twisting ofi' ofthe drill pipe during the drilling operation.

In the rotary method of drilling wells great loss often occurs due totwisting oif of the drill pipe at an intermediate point owing to thefact that it is sometimes impossible to remove the portion of the drillpipe below the point of breakage so that it becomes necessary to abandonthe hole or side-track. The theory ordinarily advanced thatsuch twistofsare caused by excessive rotating torque applied to the upper end of thedrill pipe by the rotary mechanism is apparently fallacious in view ofthe fact that greater than 200 H. P. would have to be applied to theordinary drill pipe to cause its breakage purely by torque, Whereasordinarily only 100 H. P. is available at the rotary table.

The actual cause of twist-offs is due to a combination of effects inwhich a rincipal factor is the constant reversing of exure or vbendingback and forth of a string of drill pipe which is being operated withina hole of larger diameter than such drill pipe. Due to the fatigue ofthe metal in the string of drill pipe as the result of the conditionsunder which it is operated, the ultimate strength thereof is graduallyreduced until the resistance of the drill pipe against torque is nogreater than the torque applied to the string of drill pipe by therotary mechanism, and rupture naturally follows.

It appears that under the present methods of rotary drilling breakage ofthe drill pipe cannot be prevented. The present invention thereforecomprehends a means for preventing loss of the portion of the drill pipebelow the point at which the twist-off has occurred. Y

It is an object of the invention to provide a drill pipe having one ormore definitely established points where twist-offs will occur before acondition conducive to rupture is reached in the remaining portions ofthe drill pipe, and having lifting means traversing the establishedpoint or points of rupture by which the portion of the drill pipe belowa 1929. Serial No. 371,368.

point of rupture may be lifted by the part of the drill pipe above suchpoint of rupture.

It is also an object of the invention to provide a twistofl` losspreventer or safety device which may be incorporated in a string ofdrill pipe in such manner that the device will be subjected to all ofthe conditions of torque, flexure and fatigue imposed on the string ofdrill pipe, this device having resistance to the above-mentionedconditions of torque, flexure and fatigue which is less than theresistance of the remainder of the drill pipe to such conditions,thereby causing rupture to occur in the device in advance of rupture ofthe drill pipe. @5

It is a further object of the invention to provide a tubular memberhaving coupling means at the end thereof whereby it may be incorporatedin a string of drill pipe, this tubular member having an annular groovetherein reducing the wall section of the tubular member to such anextent that rupture will occur thereat before conditions conducive torupture in the drill pipe are approached, and having a lifting means inthe form of an inner sleeve which longitudinally traverses the thusestablished point of rupture and engages above and below such point ofrupture so that the lower portion of the drill pipe-may be lifted by theupper por- 8 tion and loss of the lower portions in the well beingthereby prevented.

Further objects and advantages will be made evident throughout thefollowing part of the specification.

Referring to the drawings which are for illustrative purposes only:

Fig. 1 is a diagrammatic elevational view showing the utility of theinvention.

Fig. 2 is an enlarged vertical cross-section through my twist-olf losspreventer.

Fig. 3 is a vertical section similar to Fig. 2 but illustrating themanner in which the lower portion of a string of drill pipe below thepoint of rupture is lifted by the upper part of the string of drillpipe.

Fig. 4 is an enlarged section on a plane represented by the line 4 4 ofFig. 2.

Fig. 5 is a vertical cross-section showing 100 an alternative form oftwist-olf loss preventer having a simple and easily replaced ru turablepart.

ig. 6 is a section on a plane represented by the line 6-6 of Fig. 5.

Fi 7 is a sectional View similar to Fig. 5 showing the twist-off losspreventer after rupture has occurred and during the lifting of 1tlhelower part of the drill pipe from the we In Fig. 1 I show a string ofdrill pipe 11 extending through a well casing 12 and into the open oruncased portion 13 of a hole being drilled by a tool 14 situated at thelower end of the drill pipe 11 which consists of pipe sections 15secured together by couplings 16, there being one or more twist-off osspreventers incorporated in the string of drill pipe 11 as indicated at17. The drill ipe is rotated by means of a rotary table 18 orming partof a rotary apparatus 19, and during the drilling operation drilling mudis forced downwardly through the drill pipe 11 by means of a rotary hose20 and a swivel connection 21 which is supported from the travelingblock of the drilling rig by such means as indicated by a hook 22.

The twist-off loss preventer 17, as shown in Figs. 2 to 4 inclusive, mayinclude a. tubular member 23 having upper and lower coupling means 24and 25. The coupling means 24 preferably includes a tool joint pin 26which extends into a tool joint box 27 attached by threads 28 to thelower end of a pipe section 15, and the lower coupling means mayconveniently consist of a female threaded portion 29 formed at the lowerend of the tubular member 23 so as to `receive a tool joint pin 30 whichis screwed as indicated at 31 to the upper end of a pipe section 15.

Intermediately between the ends of the tubular member 23 an internalannular groove 32 is cut, thus reducing the thickness of theintermediate annular wall portion 33 of the tubular member 23 to such anextent that such annular wall portion 33 will be of less strength thanthe pipe sections 15 or the other members employed in making up thestring of drill pipe such as couplings and tool -oints. Extending withinthe tubular' memer 23 is a lifting means in the form of a sleeve 34having an enlargement or flange 35 at the upper end thereof whichresides in a counterbore 36 formed in the upper end of the tubularmember 23 and is adapted to engage a shoulder 37. An enlargement 38 isvpovided at the lower end of the sleeve mem.

r 34, this enlargement consisting of a Sleeve which may be secured bythreads 39 and which resides within a, counterbore 40 in the lower endof the tubular member 23.

' Rotary mud forced through the string of stresses as the remainingportions of the string of drill pipe.

The rotating torque carried from the rotary table 18 to the drillingtool 14 must be transmitted through the wall portion 33. 7o

on the string of drill pipe are also exerted v on the annular wallportion 33; therefore, this wall portion 33 being of less strength orofK less resistance to the effects of the operating conditions willrupture before a condition conducive of rupture is reached in any otherportion of the tubular drilling shaft which the pipe sections 15 andtheir coupling means form.

By use of the twist-olf loss preventer the point of twist-ofi' isdefinitely predetermined or established with the result that shouldtwist-olf occur during the drilling operation it will be confined to thewall portion 33 of the tubular member 23. In Fig. 3 a rupture 42 isindicated through the annular wall portion 33. When such rupture occursthe portion of the annular member 23 above the rupture may rotate freelyon the upper portion of the sleeve member 34. The sudden release of loadon the rotary table indicates to the operator that twist-off hasoccurred whereupon he may immediately stop the rotary table 18, and thenby lifting th'e portion of the string of drill pipe above the rupture 42may lift the portion of the \drill pipe below the rupture 42 by means ofthe lifting sleeve 34, the enlargements 35 and 38 of which provide ameans of interengagement with the shoulders 37 and 44 of the upper andlower portions of the sleeve member 23.

In Figs. 5, 6 and 7, I show an alternative form of my invention in whicha rupturable member 50, having an external wall section reducing groove51 therein, is equipped with male threads 52 and 53 on the ends thereofwhereby it may be screwed into the female threaded portions 54 and 55 ofcoupling members 56 and 57, the coupling member 56 being adapted forengagement with a tool joint box 58 threaded at 59 to the lower end of aipe section 60, and the coupling member 5 being adapted for attachmentto a tool box pin 61 which is threaded at 62 to the upper end of a pipesection 63. In this form of the invention the lifting sleeve 64 extendsentirely through the rupturable member 50 sol that the enlargements 65and 66 on the ends thereof reside in counterbores--68 and 69 in therespective coupling members 56 and 57.

When the upper portion of the string of.

drill pipe is lifted after rupture has occurred, as indicated at 70 inFig. 7, the shoulder 71 of the enlargement 65 engages the upper annularend face 7 2 of the rupturable member 50, and the shoulder 73 of thelower enlargement 66 engages the lower annular end face 74 of therupturable member 50, thereby enabling lifting of the lower portion ofthe drill pipe from the well by means of the upper portion of the drillpipe, thereby eliminating necessity for use of lishin tools and reducingto a minimum the possibllit of loss of a portion of drill pipe in awell7 due to twist-off.

In both forms of my invention the same principles are embodied. Therupturable members 23 and 50 of the respective forms shown are bothconnected into the string of drill pipe in such manner that they will besubjected to the same conditions ofv stress, torque, iexure and fatigueas any other part of the drill pipe, and being equipped with a wallstructure of relatively reduced strength or resistance to drillingconditions confine such twist-offs as may occur to predetermined pointswhere separate interconnecting and lifting means are located.

I have illustrated and described practical and operative forms of myinvention, but it is recognized that certain parts thereof arerepresentative of other parts, elements or devices whereby equivalentresults may be accomplished in substantially the same manner; therefore,the invention is not confined to the details herein disclosed but shallbe accorded the scope of the following claims.

I claim as my invention:

l. A twist-0E loss preventer of the character described, including: atubular member adapted for placement in a string of drill pipe, suchmember being subjected to the same conditions of torque, flexure andfatigue as said string of drill pipe and being made with less strengththan said drill pipe so as to rupture in advance of said string of drillpipe; and means whereby the part of said string of drill pipe below saidmember may be lifted by the part of said string of drill pipe above saidmember when said tubular member has been ruptured.

2. A twist-olf loss preventer of the character described, including: atubular member adapted for placement in a string of drill pipe, suchmember being subjected to the same conditions of torque, flexure andfatigue assaid string of drill pipe and being made with less strengththan said drill pipe so as to rupture in advance of said string of drillpipe; and means extending through said tubular member ywhereby the partof said string of drill pipe below said member may be lifted by the partof said string of drill pipeabove said member when said tubular memberhas been ruptured.

3. A twist-oli` loss preventer of the character described, including: atubular member adapted for placement in a string of drill pipe, such.member being subjected to the same conditions of torque, lexure andfatigue as said string of drill pipefand being made with less strengththan said drill pipe so as to rupture in advance of said string of drillpipe; and an inner sleeve member extending Within said tubular memberand having engagement means whereby the part of said string of drillpipe below said member may be lifted by the part of said string of drillpipe above said member when said tubular member has been ruptured.

4. A twist-off loss preventer for use in a string of drill pipe,including: an upper cou` pling member; a lower coupling member; arupturable member of less strength than said drill pipe extendingbetween said coupling members, said rupturable member being rigidlsecured to said coupling members so as to e subjected to the samestresses as said drill pipe and being made with such strength that itwill rupture before the remaining parts of said string of drill pipe;and lifting means extending longitudinally with respect to saidrupturable member.

5. A twist-off preventer fol` use in a string of drill-pipe, including:an upper coupling member; a lower coupling member; a member having anestablished point of rupture of less strength than said drill pipe, saidrupturable member extending between said coupling members and beingrigidly secured thereto so as to be subjected to the same stresses assaid drill pipe; and lifting means extending longitudinally with respectto said rupturable member, said lifting means including a tubular memberextending within said rupturable member and having enlargements at itsends engaging above and below said point of rupture.

6. A twist-ofi' loss preventer for use in a string of drill pipe,including: an u per coupling member; a lower coupling mem er; arupturable member having an established point of rupture of suchstrength that rupture will occur at said established point before therupture of the remaining parts of said string of drill pipe, saidrupturable member being adapted to carry all loads transmitted betweensaid ioupling members;

and a lifting means extending longitudinally with respect to saidrupturable member whereby said lower coupling member may be-

